1. FIELD OF THE INVENTION
The present invention relates to a filamentous microorganism detecting apparatus and an apparatus combined with the detecting apparatus for controlling a process utilizing microorganisms, or more in particular to a control apparatus for a process utilizing microorganisms which can maintain environmental conditions suitable for culturing the microorganisms high in settleability.
2. DESCRIPTION OF THE PRIOR ART
A process utilizing microorganisms, in which the metabolic function and growth function of microorganisms are used, is applied to the production of useful materials or disposal of hazardous materials. In such a process, the control of microorganisms is very important since microorganisms play the main role in reactions.
In the sewage treatment process, for instance, microorganisms called activated sludge are cultured in the system, and the organic material in the sewage is removed by use of this activated sludge. The activated sludge is separated in a settling tank and circulated for reuse to treat the sewage. If the control of the activated sludge microorganisms is improper, the settleability of the activated sludge flock (agglomerate of activated sludge) is deteriorated and flows out of the system.
This is attributable to an abnormal growth of filamentous fungi such as sphaerotilus in the microorganisms of the activated sludge. This abnormal growth, in turn, is generally caused by an improper value of (1) the dissolved oxygen concentration in the aeration tank or (2) the load of organic materials. Upon detection of the abnormal growth of filamentous fungi or a sign thereof, therefore, the process must be regulated to make the factors (1) and (2) above proper. The detection of filamentous fungi, however, requires a visual decision under microscope or measurement with curvimeter of the amount of filamentous fungi based on the photography by a skilled operator. The decision takes a long time, and if made visually, is variable depending on the operator's subjective point of view, leading to a great error.
As a result, it is actually impossible to set a control target of the dissolved oxygen concentration or the load of organic materials for the process. The control operation is thus unavoidably effected only after the abnormal growth of filamentous fungi, and the abnormal growth cannot be prevented in the initial stage of detection of filamentous fungi. The resulting disadvantages are the deterioration of the quality of the treated water or part of the activated sludge flowing out.
Another process using microorganisms involves the production of a useful material such as an antibiotic from filamentous microorganisms including bactriomycota, ascomycota, actinomycota or bacidiomycota. In the penicillin production process, for example, penicillium chrysogenum or like is cultured, while streptomyces griseus or like is cultivated in the streptomycin production process to obtain an antibiotic. The growth rate of the filamentous fungi of an antibiotic and the substrate consumption rate are known to be greatly affected by the agitation force. This is primarily caused by an increased viscosity of the broth or culture solution of filamentous fungi which the oxygen supply to the filamentous fungi and the oxygen absorption rate thereof.
Due to the difficulty of measuring the amount of filamentous fungi in the culture tank, on the other hand, it is impossible to measure the growth rate of the filamentous fungi. Generally, the amount of filamentous fungi is calculated as the weight of a solid obtained after centrifugal separation and drying processes. In this method, however, the measurement takes at least three hours, making it impossible to improve the production efficiency by maintaining proper oxygen supply.